Chapter 2: Protein Questions

Each of the 20 different amino acids has a H atom and three important functional groups attached to a central carbon atom. What are they?

1) An amino group (-NH2) 2) An acidic carboxyl group (-COOH) 3) A side chain (R-group)

A normal, lean adult body is ____% protein

12-18%

There are ___ different amino acids

20

What are two bonded amino acids called?

A dipeptide

Which of the following is/are considered fibrous proteins? Select all that apply. A: dystrophin B: insulin C: elastin D: albumin E: keratin F: fibrin

A: dystrophin C: elastin E: keratin F: fibrin

Which of the following statements regarding enzymes is TRUE? Select all that apply. A: enzymes are not altered or consumed during a reaction B: enzymes decrease the randomness of collisions between molecules C: enzymes are under the control of genes in a cell D: enzymes increase the randomness of collisions between molecules E: enzymes can exist in both active and inactive forms in a cell F: enzymes can only exist in an active form in a cell

A: enzymes are not altered or consumed during a reaction B: enzymes decrease the randomness of collisions between molecules C: enzymes are under the control of genes in a cell E: enzymes can exist in both active and inactive forms in a cell

Enzymes are specific which means they A: have a particular substrate B: have a preferred temperature C: have a preferred pH D: require a specific vitamin

A: have a particular substrate

Which of the following is/are considered fibrous proteins? Select all that apply. A: keratin B: dystrophin C: albumin D: elastin E: insulin F: fibrin

A: keratin B: dystrophin D: elastin F: fibrin

Coenzymes are derived from ______. Cofactors are derived from _____. A: vitamins B: amino acids C: metal ions D: fatty acids

A: vitamins, C: metal ions

The active site of an enzyme is the region A: where the substrate binds B: of the apoenzyme portion C: that is altered permanently during a reaction D: is where cofactors bind

A: where the substrate binds

Catalytic protein functions

Act as enzymes that regulate biochemical reactions. Examples: salivary amylase; sucrase; ATPase.

Immunological protein functions

Aid responses that protect body against foreign substances and invading pathogens. Examples: antibodies; interleukins.

Contractile protein functions

Allow shortening of muscle cells, which produces movement. Examples: myosin; actin.

The monomers (building blocks) of proteins are

Amino acids

In an amino acid, what is the minimum number of carbon atoms? Of nitrogen atoms?

An amino acid has a minimum of two carbon atoms and one nitrogen atom

_____ are proteins that defend against invading microbes

Antibodies

Which of these would be classified as a protein? A: keratin B: All of the choices are correct. C: hemoglobin D: antibodies

B: All of the choices are correct.

Regarding enzymes, induced fit means A: Is determined by the quaternary structure of a protein B: That the enzyme is capable of changing its shape in the presence of the substrate C: The enzyme is linked to a coenzyme D: The shape of enzymes is fixed

B: That the enzyme is capable of changing its shape in the presence of the substrate

Which of the following is an example of the secondary structure found in proteins? A: peptide bond B: alpha helix and beta pleated sheet C: sequence of amino acids D: a tripeptide chain

B: alpha helix and beta pleated sheet

The enzyme lipase would break down which of the following? A: proteins B: triglycerides C: carbohydrates D: ATP

B: triglycerides

Proteins are largely responsible for the structure of _____

Body tissues

The shape of a protein is A: is maintained by hydrogen bonds B: directly related to its function C: All of the choices are correct D: determined by the primary structure

C: All of the choices are correct

Molecules that contain both amino and carboxyl groups are A: Fatty acids B: Sugars C: Amino acids D: Nucleotides

C: Amino acids

Collagen is a _____________ protein. A: contractile B: regulatory C: structural D: transport

C: structural

Proteins are large molecules that contain ____, ____, ____, & ____

Carbon, hydrogen, oxygen, and nitrogen

Transport protein functions

Carry vital substances throughout body. Example: hemoglobin (transports most oxygen and some carbon dioxide in blood).

The name of an enzyme usually ends in the suffix A: -ose B: -ide C: -ate D: -ase

D: -ase

Which of the following is a characteristic of fibrous proteins? A: Fibrous proteins have structural functions B: Fibrous proteins include collagen C: Fibrous proteins are insoluble in water D: All of the choices are correct.

D: All of the choices are correct.

Which of the following is TRUE regarding enzymes? A: They are not affected by temperature or pH changes B: Their shape can vary and still be active C: They raise the activation energy of a chemical reaction D: They catalyze specific reactions

D: They catalyze specific reactions

Myosin and actin are _____________ proteins. A: transport B: structural C: regulatory D: contractile

D: contractile

The actual sequence of amino acids represents the A: tertiary structure B: quaternary structure C: secondary structure D: primary structure

D: primary structure

A protein with more than one polypeptide chain represents the A: secondary structure B: tertiary structure C: primary structure D: quaternary structure

D: quaternary structure

Regarding enzymes, induced fit means A: is determined by the quaternary structure of a protein B: the shape of enzymes is fixed C: the enzyme is linked to a coenzyme D: that the enzyme is capable of changing its shape in the presence of the substrate

D: that the enzyme is capable of changing its shape in the presence of the substrate

The process in which a protein unravels and loses its function is called

Denaturation

When two amino acids combine, a ___ is formed

Dipeptide

_____ are proteins that speed up most biochemical reactions

Enzymes

Structural protein functions

Form structural framework of various parts of body. Examples: collagen in bone and other connective tissues; keratin in skin, hair, and fingernails.

Regulatory protein functions

Function as hormones that regulate various physiological processes; control growth and development; as neurotransmitters, mediate responses of nervous system. Examples: the hormone insulin (regulates blood glucose level); the neurotransmitter known as substance P (mediates sensation of pain in nervous system).

What type of reaction takes place during catabolism of proteins?

Hydrolysis occurs during catabolism of proteins

What is the bond between two amino acids called?

Peptide bond

A ______ is a bond of 10-2000+ amino acids

Polypeptide

Secondary structure of protein

Protein structure is formed by folding and twisting of amino acid chain, stabilized by hydrogen bonds

Primary structure of protein

Sequence of amino acids

Why is it that sucrase (digestive enzyme) cannot catalyze the formation of sucrose from glucose and fructose?

Sucrase has specificity for the sucrose molecule and thus would not "recognize" glucose and fructose.

Adding another amino acid to a dipeptide produces a _____

Tripeptide

Different side chains (R-group) give each amino acid its distinctive chemical identity. T/F?

True

At the normal pH of body fluids, both the amino group and the carboxyl group are ____

ionized

Quaternary structure of a protein

results when a protein consists of multiple polypeptide chains

Tertiary structure of protein

three dimensional shape of polypeptide chain